1. Field of the Invention
The present invention relates generally to methods and systems for driving lights or other electrical devices connected to a vehicle trailer tow connector, and more specifically to methods and systems for communicating using a vehicle data communication network, and in response to network communication signals, providing electrical and mechanical connections to power lights or other electrical devices on a trailer connected to a vehicle trailer tow connector.
2. Description of the Prior Art
Motor vehicles that are designed to tow trailers frequently include a trailer tow connector near a trailer hitch or point where the trailer is connected to the towing vehicle. The trailer tow connector typically includes a plurality of connector pins or electrical connection points where power is provided from the towing vehicle to the trailer in order to power electrical devices on the trailer. Such electrical devices may include running lights, such as brake lights, parking lights, and turn signals. Other electrical devices may include back-up lights, audible back-up alerts, interior lights for lighting the inside of a trailer, cooling or ventilation fans, or other similar electrical devices. Selected pins in the trailer tow connector are usually connected to an electrical device or light that serves a particular purpose. For example, there is usually a pin for operating the brake lights on the trailer, and another pin for operating a right-hand turn signal, and yet another pin for the left-hand turn signal. Many trailer tow connectors include a pin that normally remains powered for operating devices that may be turned on and off by the user of the trailer. For example, this battery power pin may be connected to an interior dome light inside the trailer, which may be switched on and off by a person while they are working inside the trailer.
In the prior art, a common trailer tow connector has two back-to-back connectors mounted on either end of a housing, such as the arrangement shown in FIG. 1. As illustrated, trailer tow connector 20 includes connector 22 on one end of housing 24, and connector 26 on the other end. Connector 22 connects to the electrical wiring harness of the towing vehicle, while connector 26, which may be referred to as a “car end socket,” receives a trailer connector or “trailer end plug” on the trailer. Trailer tow connector 20 may include cover 28 that covers connector 26 when a trailer connector is not plugged in. Cover 28 may be pivotally mounted to mounting plate 30, which may be mounted flush against a bumper or other or plate or mounting bracket located near the trailer hitch or towing point. Housing 24 is typically cylindrical so that it passes through a punched hole in the surface to which trailer tow connector 20 is mounted.
Inside of housing 24 of prior art trailer tow connector 20 are wires that connect one pin in connector 22 directly to another pin in connector 26. Trailer tow connector 20 merely provides a transition or an adaptor between the vehicle electrical harness that is connected to connector 22 and connector 26, which is securely mounted and protected when it is not in use. Connector 26 may be a more robust connector, designed to be more frequently connected and disconnected with the wiring harness of a trailer. Cover 28 is a convenient way of protecting the connection pins in connector 26 from moisture, dirt, or mechanical abuse caused by an object striking the pins. Housing 24 provides the structure for mechanically supporting connector 22, while also protecting the wires and their connections from dirt, moisture, and other elements.
In modern vehicles, software-controlled electronics play a major role in the functioning of a vehicle's subsystems. For example, there may be eight to ten intelligent electronic modules performing functions such as controlling the engine transmission, brakes, steering, navigation, HVAC, safety, security, audio, driver information, and other similar functions. Though each function may be able to work independently, the modules may be enhanced by being connected and able to share information using an in-vehicle data communication network. Examples of such networks include Society Of Automotive Engineers (SAE) J1850, Controller Area Network (CAN), and KWP2000. These communication protocols may be used for automobile inter-module communication.
The physical communication bus of the vehicle data network may be implemented with a simple, two-wire differential serial bus system that can operate in noisy electrical-magnetic environments.
Forced by the increasing number of distributed control systems in cars and the increasing wiring costs of car body electronics, the availability of a powerful and reliable serial data communication system for the exchange of messages between the different control units is becoming important to remaining competitive in the automotive market.
Another data communication network used in vehicles is the Local Interconnect Network (LIN). LIN is used for communications and networking with a serial bus running between intelligent sensors and actuators. The LIN specification covers the data transmission protocol (the physical layer and the data link layer), and the transmission medium. The LIN bus is a class A protocol operating at a bus speed of 19,200 baud over a maximum cable length of 40 meters. LIN protocol was designed to communicate changes in switch settings and respond switch changes so that it communicates events that happen in “human” time (hundreds of milliseconds). LIN protocol supports bidirectional communication on a single wire, while using inexpensive microcontrollers. The protocol uses an autobaud step on every message. Transfer rates of up to 20 Kbaud are supported, along with a low power Sleep Mode, where the bus is shut down to prevent draining the battery, but can be powered up by any node on the bus.
When using a prior art trailer tow connector, many problems can arise that may cause hazardous or unsafe driving conditions. For example, a light on a trailer may burn out or become disconnected, which may cause a driving hazard at night or in foggy conditions. In another situation, the trailer may include electrically assisted brakes, which may fail or become disconnected, resulting in increased stopping distance that may pose a driving hazard. Many of these driving hazards arise without notification to the driver. When the driver does not know that a hazardous condition exists, the driver can not adjust driving techniques or immediately stop to fix of the failed component.
It should be apparent to those persons skilled in the art that a need exists for an improved trailer tow connector that may detect and prevent electrical problems that create driving hazards, or that may immediately alert a driver of a potentially hazardous condition in the electrical system of a trailer towed by a motor vehicle.